Panicle Sterility Research Articles

Estabilidad fenotípica de cuarenta líneas avanzadas de arroz en Babahoyo, Ecuador

The crosses between Oryza sativa L. and O. rufipogon Griff., create a high genetic diversity to develop rice varieties with high yield and phenotypic stability. In the present investigation, forty advanced lines of rice were evaluated in subsidiaries F5 (dry season) and F6 (rainy season), together with three commercial controls in the town of Babahoyo, Ecuador. A Randomized Complete Block Design (DBCA) was applied with three repetitions, recording morphoagronomic and productive characters. Statistical analyzes were applied and phenotypic stability was determined using the Eberhart and Russell, AMMI, Lin and Binns, PROMVAR models. The average morphoagronomic results were: days to flowering (72), vegetative cycle (98 days), plant height (111 cm), panicle sterility (6 %); the productive variables the results were: tillers per plant (32), panicles per plant (31), panicle length (27 cm), grains per panicle (168) and yield (8,100 kg.ha-1). The stable lines identified by the models: Eberhart and Russell were 1, 2, 10, 11, 13, 18, 25, 26, 30 and 37; AMMI identified lines 8 and 22; Lin and Binns to lines 2, 12, 18, 27, 37 and 40; and PROMOTE lines 2, 10, 13, 18, 25, 30, 38, 40 and 43; concluding that seven lines (2, 10, 13, 18, 25, 30 and 40) coincided with the applied models except AMMI. The average yield of the lines mentioned in the two seasons was 7,797 kg.ha-1, higher than the average of the commercial controls that obtained 6,809 kg.ha-1.

Major challenges in widespread adaptation of aerobic rice system and potential opportunities for future sustainability

Climate change and diminishing resources are the major challenges in sustainable rice production. The aerobic rice system can be a transformational approach to replace conventional rice in the face of climate change and scarcity of resources due to its high input-use efficiency. However, it could not be adapted widely yet due to several challenges like higher weed infestation and low nitrogen (N) use efficiencies. This transformed system can only be adapted at a wider scale through investigation of associated constraints and risks and provision of potential adjustive measures. Aerobic rice crop failure can be reduced if the availability of suitable and stress-resistant cultivars with early improved vigour, and short-duration characteristics are ensured for maintaining the reproductive capability under resource stressed environment. This transformed rice system exhibits limited response to applied N because of increased losses due to higher volatilization and rapid coupled nitrification-denitrification processes under alternate wetting and drying systems. Shifting from the flooded to aerobic rice system bringing changes in crop water demand, organic matter (OM) turnover, N dynamics, weed flora, and greenhouse gases (GHGs) emissions. Along with N-losses, continuous monocropping, higher weed infestation, weedy rice emergence, nitrous oxide (N2O) emissions, nutrient disorders, higher prevalence of pathogens and diseases, increased panicle sterility, and an increase in soilborne pathogens lodging are other major constraints negatively impacting the widespread adaptation of aerobic rice. This article reviews the climate change status, its associated impacts on the sustainability of traditional rice systems, and the rationale for transforming from traditional to aerobic rice systems. Furthermore, it describes the major challenges associated with the aerobic rice system, thereby presenting management strategies ensuring its wider adaptation for sustainable rice production in the face of projected climate change and scarcity of resources.

First report of rice bacterial leaf blight disease caused by Pantoea ananatis in the United States.

In August 2021, bacterial leaf blight-like symptoms were observed on 14 out of 570 rice genotypes (Oryza sativa) in research field plots of global rice germplasm grown in Arkansas (eXtra Figure S1. A & B). The disease was characterized by spreading lesions on leaves, panicle sterility and reduced yield in highly susceptible, mature rice germplasm. No spread of disease to nearby plants was observed. Isolations were performed at Colorado State University, where soakates from symptomatic leaves were spread onto nutrient agar. After 72 h at 28°C, uniform, distinct, yellow-colored bacterial colonies were observed. To screen for the presence of common rice bacterial pathogens, PCR amplification directly from colonies or from DNA isolated from symptomatic field-collected leaves was performed. Primers specific for Xanthomonas oryzae pvs. oryzae and oryzicola (Lang et al., 2010), Burkholderia glumae (Echeverri-Rico et al., 2021), and Pseudomonas fuscovaginae (Ash et al., 2014) did not amplify indicating these organisms were not present. Sequencing of 16S rRNA gene (Weisburg et al., 1991) amplicons suggested the bacteria belonged to the genera Pantoea and Sphingomonas (NCBI accession no. OP683332 and OP683333, respectively). Amplicons resulting from primers specific to the gyrB gene region of P. ananatis (Kini et al., 2021) were sequenced and the fragment was compared to the P. ananatis PA13 reference genome using a BLAST analysis. One candidate (AR358) showed 100% identity with the P. ananatis gyrB region. Primers specific for Sphingomonas sp. (Bangratz et al., 2020) confirmed the second candidate (AR359) as a Sphingomonas sp. The identity of P. ananatis was confirmed by the Plant Pathogen Confirmatory Diagnostics Laboratory (Beltsville, MD, USA). To determine pathogenicity, leaves from 7-day-old seedlings of rice (Oryza sativa) cultivar Kitaake were scissor-clip inoculated (Kauffman et al., 1973) with four different treatments and compared to control leaves inoculated with sterile water. Treatments for the experiment consisted of bacterial suspensions (108 CFU/ml) of the two candidate organisms, P. ananatis (strain AR358) or Sphingomonas sp. (strain AR359), individually or in a 1:1 ratio of P. ananatis:Sphingomonas sp., or soakate from infected field tissue. Lesions similar to those observed in the field were only detected on leaves inoculated with P. ananatis or infected field tissue soakate at 7-days post-inoculation (eXtra Figure S1. C). Bacteria were recovered from the leaves of the artificially inoculated seedlings from three treatments (P. ananatis, P. ananatis:Sphingomonas sp. and soakate from the infected field tissue) and were determined to be P. ananatis based on colony morphology, amplification of 16s rRNA, and gyrB sequence data. Our results confirm the pathogenicity of P. ananatis to rice and fulfill Koch's postulates. P. ananatis was also recovered from several similarly diseased rice breeding lines at the University of Arkansas System Division of Agriculture Rice Research and Extension Center. We conclude that P. ananatis is the causal pathogen for leaf blight-like symptoms observed in the global rice cultivars grown in Arkansas. P. ananatis was previously reported as a pathogen on rice in several rice growing regions, including China (Yu et al., 2021), India (Reshma et al., 2022), and Africa (Kini et al., 2017), however, this is the first report of P. ananatis as a pathogen of rice in the United States.

Registration of two novel grain sorghum nuclear male sterile mutants: BTx623ms9‐1 and BTx623ms9‐3

AbstractThe USDA‐ARS has released two new sorghum [Sorghum bicolor (L.) Moench] nuclear male sterile (NMS) mutants, BTx623ms9‐1 (Reg. no. GS‐791, PI 699654) and BTx623ms9‐3 (Reg. no. GS‐792, PI 699655). Both mutants were isolated from an ethylmethane sulfonate mutagenized population developed in the inbred line BTx623 and displayed stable male sterility across two environments tested. The homozygous BTx623ms9 panicle produces normal ovaries but small pale‐colored anthers with no pollen grains, making it easy to identify the sterile from the fertile panicles at the start of anthesis. Other than male sterility, the ms9 mutants are indistinctive from BTx623 wild type in morphology and development. Analyses indicate that the male sterility in BTx623ms9 mutants is controlled by recessive mutations on a single nuclear gene and differs from those that are available in currently known NMS lines (ms1, ms2, ms3, ms7, and ms8). The BTx623ms9‐1 and the BTx623ms9‐3 mutants harbor a nonsynonymous mutation (R218A) and a knockout mutation in the gene Sobic.002G221000, respectively. The causal mutations can be used to design molecular markers for efficient introduction of the Ms9 mutations into other sorghum lines. These two released NMS lines segregate for 50% pure male sterile and 50% fertile (Ms9/ms9) plants and can be maintained by pollinating sterile panicles with the pollen of the fertile plants. The two mutants can serve as female parents to create new mapping populations for genetic analysis and for evaluation of experimental hybrids.

Relationships Among Arsenic-Related Traits, Including Rice Grain Arsenic Concentration and Straighthead Resistance, as Revealed by Genome-Wide Association.

There is global concern that rice grains and foods can contain harmful amounts of arsenic (As), motivating breeders to produce cultivars that restrict As accumulation in grains to protect human health. Arsenic is also toxic to plants, with straighthead disorder (StHD), causing panicle sterility, being observed in rice. The genetic variation in StHD resistance suggests that plants have evolved mechanisms that reduce As toxicity, possibly via regulation of As uptake, transport, or detoxification/sequestration. Because these mechanisms could also underlie the wide (3- to 100-fold) differences in grain As concentration (grain-As) observed among diverse rice genotypes, it was hypothesized that some genes reduce both grain-As content and StHD susceptibility and may be detectable as co-located StDH and As quantitative trait loci (QTL). We used a machine-learning Bayesian network approach plus high-resolution genome-wide association study (GWAS) to identify QTL for grain-As and StHD resistance within the USDA Rice Minicore Collection (RMC). Arsenic enters roots through phosphorus (P) and silica (Si) transporters, As detoxification involves sulfur (S), and cell signaling to activate stress tolerance mechanisms is impacted by Si, calcium (Ca), and copper (Cu). Therefore, concentrations of Si, P, S, Ca, and Cu were included in this study to elucidate physiological mechanisms underlying grain-As and StHD QTL. Multiple QTL (from 9 to 33) were identified for each of the investigated As-associated traits. Although the QTL for StHD, Si, and grain-As did not overlap as heavily as our hypothesis predicted (4/33 StHD and 4/15 As QTL co-located), they do provide useful guidance to future research. Furthermore, these are the first StHD and Si QTL to be identified using high-density mapping, resulting in their being mapped to shorter, more precise genomic regions than previously reported QTL. The candidate genes identified provide guidance for future research, such as gene editing or mutation studies to further investigate the role of antioxidants and ROS scavenging to StHD resistance, as indicated by candidate genes around the commonly reported qStHD8-2 QTL. Other genes indicated for future study for improving grain-As and StHD include several multidrug and toxic compound extrusion (MATE) genes, F-box genes, and NIPs not documented to date to transport As.

Review On Scope And Challenges Of Direct Seeded Rice In Nepal

Rice is an important staple food crop of more than half of the population in the world to provide food security and livelihoods. Imminent water crisis due to climate change, water demanding nature of traditionally cultivated rice, increasing scarcity of labor and escalating labor costs drive the search for alternative management methods to increase water productivity, system sustainability and profitability in rice cultivation. Direct seeded rice (DSR) technique has received much attention and popularity nowadays because of its low-input demanding nature that can mitigate emission of green-house gases and adaption to climatic risks. DSR involves sowing of dry seed into a prepared seedbed, pre-germinated seed into a puddled soil surface and standing water. The development of early maturing varieties and use of efficient nutrient management practices along with increased adoption of integrated weed management techniques have encouraged many farmers to switch from transplanted to DSR culture. DSR technology is highly mechanized in some developed countries like USA, Australia, Japan, China, Korea etc. This shift from traditional rice to DSR will substantially reduce crop water requirements, soil organic-matter turnover, enhanced nutrient management, carbon sequestration, weed management, greenhouse-gas emissions and enhance crop intensification. However, weed and nematode infestation, blast, panicle sterility, lack of suitable varieties for DSR and lodging are major challenges. Based on existing evidences, this paper reviews the integrated package of technologies for DSR, potential advantages and challenges associated with it.

DPS1 regulates cuticle development and leaf senescence in rice

AbstractLeaves are the primary food‐producing organs for a plant that carry out photosynthesis and contribute to biomass and grain yield. Leaf senescence is a developmentally regulated physiological process but early leaf senescence is known to negatively affect plant yield. The cuticle is an outer waxy protective layer on the leaf surface which protects plants from pathogens attack as well as dehydration. Our understanding of the molecular mechanisms underlying cuticle development and leaf senescence is still immature. The present study reports the role of the DEGENERATED PANICLE AND PARTIAL STERILITY 1 (DPS1) gene encoding a cystathionine β‐synthase (CBS) domain‐containing protein in cuticle development and leaf senescence in rice. The dps1 loss‐of‐function mutant showed leaf senescence phenotype with twisted leaves, significantly reduced chlorophyll content and degenerated chloroplasts characterized by a reduced number of starch granules and an abundance of osmiophilic bodies. Furthermore, dps1 leaves displayed defective cuticle development, reduced wax and cutin compounds, and lower relative water content as compared with wild type. Physiological assays showed significantly higher accumulation of reactive oxygen species (ROS) accompanied by enhanced DNA fragmentation in dps1 leaves, which could be associated with chloroplast degeneration and defective cuticle development. Transcriptome analysis revealed altered expression of several critical genes related to photosynthesis and wax/cutin pathway. This study revealed a crucial role of DPS1 in regulating leaf cuticle development and senescence by affecting the expression of several genes. Thus, a moderate expression of DPS1 is necessary for better plant growth and productivity.

Halo and UV-B priming influences various physiological and importantly yield parameters of Oryza sativa var. Vyttila 6

ABSTRACT Photosynthetic activity and remobilisation of nutrients during the reproductive phase of rice are detrimental factors, directly linked with crop productivity. The objective of this study was to determine the priming efficacy on different physiological features such as generation of reactive oxygen species (ROS), accumulation of malondialdehyde, activities of enzymatic and content of non-enzymatic antioxidants and chlorophyll a fluorescence measurements at booting, silking and mature stages of rice in response to UV-B and halo priming. Seed priming reduced the excess ROS generation and oxidative stress through positive regulation of the antioxidation mechanism. The effective antioxidant machinery in UV-B and halo primed plants ensured that the photosynthetic process proceeded uninterruptedly, ensuring the efficacy of the same even when encountered with oxidative stress. The present study proves that halo and UV-B priming of seeds reduced panicle sterility, increased the harvest index, at the reproductive phase of the plant. Halo and UV-B priming retained priming imprints throughout the plant life cycle ultimately leading to the increased yield-related parameters in Vyttila 6.

Assessment of the roles of SPO11-2 and SPO11-4 in meiosis in rice using CRISPR/Cas9 mutagenesis.

In Arabidopsis, chromosomal double-strand breaks at meiosis are presumably catalyzed by two distinct SPO11 transesterases, AtSPO11-1 and AtSPO11-2, together with M-TOPVIB. To clarify the roles of the SPO11 paralogs in rice, we used CRISPR/Cas9 mutagenesis to produce null biallelic mutants in OsSPO11-1, OsSPO11-2, and OsSPO11-4. Similar to Osspo11-1, biallelic mutations in the first exon of OsSPO11-2 led to complete panicle sterility. Conversely, all Osspo11-4 biallelic mutants were fertile. To generate segregating Osspo11-2 mutant lines, we developed a strategy based on dual intron targeting. Similar to Osspo11-1, the pollen mother cells of Osspo11-2 progeny plants showed an absence of bivalent formation at metaphase I, aberrant segregation of homologous chromosomes, and formation of non-viable tetrads. In contrast, the chromosome behavior in Osspo11-4 male meiocytes was indistinguishable from that in the wild type. While similar numbers of OsDMC1 foci were revealed by immunostaining in wild-type and Osspo11-4 prophase pollen mother cells (114 and 101, respectively), a surprisingly high number (85) of foci was observed in the sterile Osspo11-2 mutant, indicative of a divergent function between OsSPO11-1 and OsSPO11-2. This study demonstrates that whereas OsSPO11-1 and OsSPO11-2 are the likely orthologs of AtSPO11-1 and AtSPO11-2, OsSPO11-4 has no major role in wild-type rice meiosis.

Identification and characterization of the stunted sterile (ss) mutant in rice.

Proper organ development is pivotal for normal rice growth and production. Many genes are involved in this process, and these genes provide a basis for rice breeding. To identify a novel mutation causing developmental defects in rice. The phenotype of a rice mutant, stunted sterile (ss), identified from the japonica rice cultivar Samkwang treated with N-methyl-N-nitrosourea, was characterized, including anatomical and pollen activity analyses. A genetic analysis and fine mapping were performed to identify a candidate locus, followed by a sequence analysis to determine the causal mutation for the phenotype. Compared with wild-type plants, the mutant exhibited a 34% reduction in height, 46% reduction in flag leaf width, and complete panicle sterility. Cell proliferation in the leaf and pollen viability were significantly inhibited in the mutant. The mutant phenotypes were controlled by a single recessive gene that was fine-mapped to an 84 kb region between two SNP markers on the short arm of chromosome 5. A candidate gene analysis determined that the mutant carries an 11 bp insertion in the coding region of LOC_Os05g03550, which encodes a protein containing two SANT domains, resulting in a premature termination codon before the conserved domain. We identified a novel rice gene, Stunted sterile, involved in the regulation of various developmental processes. Our findings improve our understanding of the role of chromatin remodeling in organ development and have implications for breeding owing to the broad effects of the gene on plant growth.

Syringopeptin Contributes to the Virulence of Pseudomonas fuscovaginae, Based on sypA Biosynthesis Mutant Analysis.

Pseudomonas fuscovaginae, first reported from Japan in 1976, is now present in many agroecological regions around the world; it causes sheath brown rot of rice and is reported as a pathogen of a broad range of hosts. The pathogen can infect rice plants at all stages of growth and is known to cause significant losses due to grain discoloration, poor spike emergence and panicle sterility. Limited information is available on the virulence and mechanisms of pathogenicity for P. fuscovaginae. To address this, an analysis of genomes was conducted, which identified the presence of a gene showing homology to one of the genes contributing to syringopeptin synthetase (sypA) of P. syringae pv. syringae. To study the potential role of this gene in the virulence and pathogenicity of P. fuscovaginae, a site-specific mutation was created. Following inoculation of seeds and plantlets of rice and wheat with P. fuscovaginae wild types and their respective mutants, we demonstrated that the mutation significantly reduced virulence. This was evident on rice and wheat inoculated with mutants causing a significantly higher number of roots, length of roots and seedling height compared with their respective wild types. Characteristic disease symptoms of necrotic lesions were significantly less in rice seedlings infected with bacterial suspensions of mutants indicating a reduction in virulence. Chromatography analysis of bacterial exudates showed suppression of synthesis of metabolites analogous to syringopeptin in the mutants. These data demonstrate that the protein encoded by this sypA homolog gene is a major virulence determinant of P. fuscovaginae.

The Genetic Variability of Floral and Agronomic Characteristics of Newly-Bred Cytoplasmic Male Sterile Rice

Male sterility enabled commercialization of heterosis in rice but low seed set remains a constraint on hybrid dissemination. We evaluated 216 F6 maintainer lines for agronomic and floral characteristics in augmented design and selected 15 maintainer lines, which were testcrossed with IR58025A. Five backcrosses were conducted to transfer cytoplasmic male sterility (CMS) to select maintainer lines. Newly-bred BC5:6 CMS lines were evaluated for outcrossing rates and agronomic characteristics. There were highly significant differences among 216 F6 maintainer lines for characteristics whose genotypic variance was higher than environmental variance. The phenotypic coefficient of variation was almost the same as the genotypic coefficient of variation, indicating that most phenotypic variation was due to genetics. There were highly significant differences among CMS lines for number of days to 50% flowering and maturity; stigma exertion; panicle exertion, length and weight; spikelet fertility; tillers per plant; plant height; grains per panicle; grain yield per plant; and 1000-grain weight, but not for pollen and panicle sterility during dry and wet seasons. Three CMS lines (CMS3, CMS12, and CMS14), exhibited high outcrossing rates (56.17%, 51.42% and 48.44%, respectively), which had a highly significant, positive correlation with stigma exertion (0.97), spikelet opening angle (0.82), and panicle exertion (0.95).

Production Determinants of the Pearl Millet Cropping System in Uganda and Implications to Productivity

<p>Pearl millet is an important crop for people living in semi-arid areas in Uganda but not much is known about its production environment. A survey was conducted in eastern and northern regions of Uganda to characterise the pearl millet cropping system and to identify the most important production determinants. Using questionnaires, data was collected from 160 households through face-to-face interviews with the respondents. Results showed that pearl millet was mainly grown for food and source of income. The production environment was low input as farmers planted unimproved genotypes, used no artificial chemicals or manure, and had minimal access to financial credit and agricultural trainings or extension services. Planting was done in the second rains with no optimal use of important resources like family labour and seed due to seed broadcasting. Farmers desired genotypes with traits such as; stay green, being tall, high tillering, high yield, early maturity and being ergot resistant. The most important constraints were ergot and rust diseases susceptibility, low yield, low tillering, late maturity, sterile panicles, rodents, moulds/rotting and insect pests; while lack of market, low prices and price fluctuation were the important market constraints. Results further showed that farmers lacked knowledge about the common diseases like rust and ergot. The area planted, spouse age and years of pearl millet cultivation were the important factors enhancing production while age of household head, amount of seed planted and distance to the market negatively affected grain yield.</p>

English

Rice is one of the important cereal crops drastically affected by water scarcity in rice ecosystems. In a pot study, the impact of externally applied gibberellic acid (GA3), indole acetic acid (IAA) and kinetin was investigated on assimilates mobilization and yield parameters of rice under water stress. Twenty five days seedlings of two rice genotypes KS-133 and Basmati-2000 were transplanted in soil filled pots and sprayed with GA3, IAA and kinetin each of 10 M concentration at panicle initiation stage. Water stress was imposed to plants 80 days after transplanting for 10 days. Water stress (p≤ 0.05) reduced leaf chlorophyll content and yield of rice but increased the concentration of proline, leaf soluble protein and enhanced mobility of assimilates from leaves to grains. Application of GA3 and kinetin significantly (p≤ 0.05) increased chlorophyll content, growth and yield attributes in both genotypes under water stress conditions. However, IAA application did not improve the grain yield in rice genotypes under water stress. The positive impact of GA3 and kinetin spray was imitated in the form of enhanced solute accumulation; enhanced growth and greater grain assimilate deposition. This may be concluded that GA3 and kinetin can be applied exogenously prior to flower initiation in rice to reduce panicle sterility by increasing assimilates mobility under water deficit for optimal economic yield. © 2016 Friends Science Publishers

Improving the performance of short-duration basmati rice in water-saving production systems by boron nutrition

Over exploitation of groundwater and decreasing canal water resources are threating the productivity of conventional rice production systems in Asia which is the main rice bowl. Therefore, strategies are needed to produce more rice with less water in the shortest possible duration without compromising the yield to feed the increasing world population. Panicle sterility is one of the major obstacles in wide‐scale adoption of water‐saving rice production systems. Boron (B) deficiency, in water‐saving rice production systems, has been identified as a possible reason for panicle sterility. This 2‐year field study was aimed to investigate the potential of pre‐optimised boron application through various methods in improving the productivity of short‐duration basmati rice (Shaheen Basmati) in water‐saving production systems, as delivered through seed priming (0.1 mM boron), foliar spray (200 mM boron) or soil application (1 kg boron ha⁻¹), while hydropriming and no boron application were taken as control. Boron nutrition, by either way, improved the growth, water relations, morphology, yield‐related traits, panicle fertility, grain yield, grain quality and grain boron contents of short‐duration basmati rice; nonetheless, boron application as seed priming was superior and cost effective with maximum marginal rate of return. In conclusion, boron nutrition through seed priming is cost effective and may help improving the productivity, quality, and boron grain contents in short‐duration basmati rice under water‐saving production systems.

WATER SAVING, WATER PRODUCTIVITY AND YIELD OUTPUTS OF FINE-GRAIN RICE CULTIVARS UNDER CONVENTIONAL AND WATER-SAVING RICE PRODUCTION SYSTEMS

SUMMARYIn this study, we compared the weed emergence, water input, water saving, water productivity, panicle sterility, yield outputs and economic returns of transplanting with alternate wetting and drying (TRAWD) and dry direct seeding (DSR) with transplanting under continuous flooding (TRCF) using three fine-grain rice cultivars: Super Basmati; Basmati 2000; and Shaheen Basmati. Higher weed infestation was recorded in DSR than in TRCF and TRAWD. Raising rice as TRAWD and DSR had considerable water savings but a lower grain yield than TRCF. High panicle sterility was primarily responsible for low grain yield in TRAWD and DSR systems. Nonetheless, water productivity was better in DSR and TRAWD than TRCF. Shaheen Basmati in the DSR system and Basmati 2000 in TRCF fetched the highest economic returns during 2008 and 2009, respectively. In conclusion, fine-grain rice cultivars can be grown in water-saving production systems (e.g. TRAWD and DSR); however, these water-saving production systems might incur a yield penalty.

Soil Application of Boron Improves the Tillering, Leaf Elongation, Panicle Fertility, Yield and its Grain Enrichment in Fine-Grain Aromatic Rice

Boron (B) is one of the essential micronutrients having a specific role, particularly during reproductive phase, in rice. In a previous experiment on aerobic rice, panicle sterility was noted as one of the major challenges. This experiment was conducted to evaluate the influence of soil-applied B on tillering, panicle sterility, water relations, and grain enrichment in fine-grain aromatic rice cultivars ‘Super Basmati’ and ‘Shaheen Basmati’. Boron was soil applied at 0.50, 0.75, 1, 1.25, and 1.50 kg ha−1 while the control treatment did not receive B. Rate of leaf emergence and elongation and tiller appearance were significantly improved by B application. Likewise, B application also improved the leaf chlorophyll contents and water relations in both rice cultivars. Substantial improvement in kernel yield and yield contributing traits was also observed by B application owing to decrease in panicle sterility. A linear increase in leaf and kernel B contents was observed with increase in B application rate. However, the range for an optimum B application rate is very narrow and increase of B application beyond 1 kg ha−1 was toxic. In conclusion, soil application of B is an effective way to decrease panicle sterility and increase the kernel yield and grain B enrichment in rice.

Metabolism of reactive oxygen species in cytoplasmic male sterility of rice by marking upmost pulvinus interval.

Reactive oxygen species (ROS) and malondialdehyde (MDA) in plant cell are thought to be important inducible factors of cell apoptosis if excessively accumulated in cells. To elucidate the metabolic mechanism of MDA production and scavenging in the cytoplasmic male-sterile (CMS) rice, CMS line and maintainer were employed for studying the relationship at different developmental stages by marking upmost pulvinus interval method of experiment. The results showed that the panicles and leaves of the CMS line had a noticeable higher MDA content than those of maintainer line at all five stages that had been investigated (p < 0.05). MDA content in the CMS line in the flag leaves of auricle in the distance 0 mm stage (the meiosis stage) was the highest of the five stages. The increase of MDA contents in sterile panicles and leaves had inducible effects on the enzymic activity of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). However, at the abortion peak stage, MDA was excessively accumulated and antioxidant enzymic activity reduced significantly, resulting in the generation and scavenging of MDA out of balance.

Influence of boron nutrition on the rice productivity, kernel quality and biofortification in different production systems

Boron (B) deficiency is becoming a common problem in water-saving rice production systems of South Asia. Boron nutrition can potentially improve the crop performance. This two-year field study was conducted to evaluate the potential of pre-optimized B application through various methods in improving the performance of rice grown in aerobic culture, alternate wetting and drying and flooded systems. Boron was delivered as seed priming (0.1mM B), foliar spray (200mM B), and soil application (1kgBha−1); no B application and hydropriming were taken as control. Boron nutrition by either method improved the plant water relations, total chlorophyll contents, morphological and yield related traits in different rice production systems. In addition to improvement in kernel yield, boron application also improved the kernel quality. Foliar application of boron in flooded rice and alternate wetting and drying gave maximum net returns than all other treatment combinations. In crux, B application through foliar spary or seed priming may be an economically viable option to reduce panicle sterility, improve kernel quality, rice growth and yield. Improvement in rice yield by B application is attributed to increase in kernel size and decrease in panicle sterility.

Foliage applied boron improves the panicle fertility, yield and biofortification of fine grain aromatic rice

Boron (B) deficiency in rice field is becoming a common problem in South Asia. Correcting B deficiency in rice has potential to improve the rice productivity. Foliage application of B is an easy and effective way to resolve this problem. This study was conducted to evaluate the influence of foliage applied (0.16, 0.24, 0.32, 0.40 and 0.48 M) B on leaf elongation, tillering, water relations, yield and B grain enrichment of rice cultivars Super Basmati and Shaheen Basmati. Foliage applied B improved leaf elongation, tillering, leaf chlorophyll contents, water relations, grain yield, yield-related traits and B grain contents with simultaneous decrease in panicle sterility. However, foliage application of 0.32 M B was the most effective in this regard. An increase in leaf and grain B contents was observed with increase in B concentration in the foliar spray. There was no difference between the cultivars for grain yield; however, Shaheen Basmati had more grain weight, and grain and leaf B contents than Super Basmati. Boron foliage application (0.32 M B) proved an effective way to correct B deficiency in rice. Improvement in grain yield by B application was attributed to increase in grain size and decrease in panicle sterility.